Contact spring set for an electromagnetic relay

ABSTRACT

An electromagnetic relay has a contact spring set in which the contact springs are held in fixed position between two plastic base members, one of which is thermoplastic and is secured to the other by deforming the thermoplastic material during heating by ultrasonic means. The contact springs are aligned in the correct position during assembly by means of registration surfaces mounted on the base member which is not deformed during assembly.

United States Patent Schedele et al.

[ Oct. 15, 1974 1 1 CONTACT SPRING SET FOR AN ELECTROMAGNETIC RELAYInventors: [lelrnpt schedele l loegling; Werner Bosch, Munich, both ofGermany Siemens Aktiengesellschaft, Berlin and Munich, Germany Filed:Apr. 6, 1973 Appl. No.: 348,683

Assignee:

Foreign Application Priority Data Apr. 10, 1972 Germany 2217218 US. Cl200/283, 29/622, 200/303 Int. Cl H0lh 1/26, l-10lh 9/02 Field of Search200/166 J, 1 A, 168 R;

References Cited UNITED STATES PATENTS 12/1967 Simon 200/166 .1 X

3,377,450 4/1968 Grady et al. 200/166 .1

3,437,772 4/1969 Piber 200/166 .1 3,485,982 12/1969 Maire 200/166 .1 X

Primary Examiner-Robert K. Schaefer Assistant Examiner-William J. SmithAttorney, Agent, or FirmHill, Gross, Simpson, Van Santen, Steadman,Chiara & Simpson [5 7 ABSTRACT An electromagnetic relay has a contactspring set in which the contact springs are held in fixed positionbetween two plastic base members, one of which is thermoplastic and issecured to the other by deforming the thermoplastic material duringheating by ultrasonic means. The contact springs are aligned in thecorrect position during assembly by means of registration surfacesmounted on the base member which is not deformed during assembly.

17 Claims, 9 Drawing Figures PATENIEBOCT 51974 SHEET 5 OF 6 CONTACTSPRING SET FOR AN ELECTROMAGNETIC RELAY BACKGROUND 1. Field of theInvention The present invention relates to a contact set for anelectromagnetic relay, and more particularly to such a contact set whichis adapted for mechanized assembly.

2. Prior Art Progress in the art of electromagnetic relays has led tothe development of ever smaller and more compact arrangements, in whichthe magnetic system of the relay and the electrical conducting partsthereof are arranged as close to each other as possible. It has becomecommon to mount the contact springs separately from the coil of themagnetic circuit, either to the side of the yoke of the magnet, or belowit, and this arrangement is especially advantageous for use with relayconstructions in which a minimum height is desired for the relay, as inso-called card relays.

These relays, and miniature relays of other types, require very carefulsoldering in connecting the terminals of the relays, to protect theelectrical contact springs of the relay from damage, as the terminalsare located quite near to the contact springs. In order to furnish ameasure of protection to the contact springs, the solder connections aresometimes passed through apertures in a separate base plate, formed ofinsulating material, and the soldering takes place on the opposite sideof the plate from the contact springs. However, space around the edge ofthe apertures, allows contaminating vapors to pass through theapertures, which degrade the performance of the contact springs.

It has been proposed to employ a block of insulation material havingrecesses or chambers in which the contact springs are located, so thatthe operative parts of the contact springs are protected by beingisolated from the solder terminals, and insulated from other conductiveparts. For example, the German Gebrauchsmuster 6,601,156 illustrates acontact spring set having a single block of insulating material,provided for all of the contact springs, which are in the form of wiresprings. In this arrangement, the contact springs are located inrecesses in the block. However, this construction has the disadvantagethat the correct placement of the contact springs during assembly of therelay is very difficult to mechanize.

SUMMARY OF THE INVENTION It is a principal object of the presentinvention to provide a contact spring set for a relay having means forprotecting the contact springs from damage during soldering, and forinsulating the contact springs from the electrically conductive members.

Another object of the present invention is to provide such a contactspring set which is readily adaptable to being assembled and constructedby a highly mechanized process.

A further object of the present invention is to provide such a contactspring set in which the contact springs may be placed in positionrelative to an insulating-base member prior to assembly of theapparatus.

Another object of the present invention is to provide such a contactspring set in which only two insulating- In one embodiment of thepresent invention, there is provided a contact spring set including ablock of insulating material formed of an upper base member and a lowerbase member, said contact springs being interposed between the two basemembers and fixed in position in relation to one of said base members.

BRIEF DESCRIPTION OF THE DRAWINGS Reference will now be made to theaccompanying drawings in which:

FIG. 1 is an end elevation view of an electromagnetic card relay havinga contact spring set formed in accordance with an illustrativeembodiment of the present invention;

FIG. 2 is a perspective view of a portion of the apparatus of FIG. 1;

FIG. 3 is an exploded perspective view of a portion of the apparatusillustrated in FIGS. 1 and 2, illustrating the manner of assembly of oneof the contact springs;

FIG. 4 is a vertical cross sectional view of a portion of the apparatusillustrated in FIG. 3, when in assembled condition;

FIG. 5 is a vertical cross sectional view of the apparatus of FIG. 4,taken along the section line VV;

FIG. 6 is an exploded perspective view of a portion of the apparatus ofFIGS. 1 and 2, illustrating the manner of assembly of a second contactspring;

FIG. 7 is an exploded perspective view of a portion of the apparatus ofFIGS. 1 and 2, illustrating the manner of assembly of a third contactspring;

FIG. 8 is a vertical cross sectional view of a portion of the apparatusillustrated in FIG. 7, after assembly; and

FIG. 9 is a horizontal cross sectional view of a portion of theapparatus illustrated in FIG. 8, taken along the section line IX-IX.

DESCRIPTION OF THE PREFERRE EMBODIMENTS Referring now to FIG. I, inwhich a so-called card relay is illustrated, the insulating block of therelay is made up of a lower base member 1 and an upper base member 2.The base members 1 and 2 are both formed of insulating material, and areassembled in such a way as to hold various contact springs 8, 9 and 10in correct relationship, after assembly. The contact springs 8 and 9 arefixed contacts of the relay and the contact spring 10 is a movablecontact spring, normally closing an electrical circuit with the uppercontact spring 8, but opening that circuit and closing an electricalcircuit with the contact spring 9, when the relay is operated.

A magnet system is provided for operation of the relay, and the magnetsystem incorporates a yoke 3, a coil 4 supported by the yoke 3, and anactuating member 5 having a depending projection 7. When the relay isactuated by passing a current through the coil 4, the actuating member 5functions to lower the projection 7 against the free end of the contactspring 10, to change the position of the contact spring 10. The magnetsystem is typically a separate assembly, and is connected with thecontact spring set by means of a bracket 6, adapted to engage notchesprovided in opposite side portions of the base members 1 and 2, and heldthereby when the magnet assembly and contact spring set are assembled.

As best shown in FIG. 2, the contact sets comprise two separate singlepole double-throw switches, one being located on either side of the basemembers 1 and 2. The actuating member 5 is provided with two projections7, one for each of the movable contact springs 10 and 10' of the twoswitches. As the two switches are identical, except for their positionrelative to the base members 1 and 2, the construction and operation ofonly one of the contact spring sets need be described in detail.

As best shown in FIG. 2, one of the contact spring sets is arranged in arecess 11 having a side wall defined by a side surface of the basemembers 1 and 2, and having lower and upper walls defined by a portion1a of the lower base member 1 projecting outwardly below the recess 11,and a corresponding portion 2a of the upper base member 2 extendingoutwardly above the recess 11. The three contact springs 8, 9 and 10have portions which are anchored between the base members 1 and 2, andare maintained in correct position thereby.

Each of the base members 1 and 2 are formed as a relatively flat plasticconstruction, having a central recess or aperture 12 designed toaccommodate the magnetic coil 4. Each of the three contact springs 8, 9and 10 have an individual terminal part 8a, 9a and 10a, by whichelectrical connections to the control springs may be made by soldering.As shown in FIG. 2, the contactmaking part 8!: of the upper contactspring is positioned at the upper portion of the recess 11, and thecontact-making part 9b of the contact spring 9 is positioned directlytherebelow, The contact-making part 10b of the contact spring 10 ispositioned between the contact-making parts of the contact springs 8 and9, and is adapted to make electrical contact with one or the other inaccordance with the condition of the actuating member 5. The recess 11may be referred to as a circuit chamber, since it is isolated from themagnet assembly by the overlying portion of the upper base member 2, andisolated from the terminal parts 8a, 9a and 10a by the underlyingportion of the lower base member 1.

The lower base member 1 is formed of a plastic material having arelatively high melting point, in order to provide mechanical integrityat the time heat is applied to the upper base member during assembly.The upper base member is formed of thermoplastic material so thatapplication of heat thereto results in a softening and deforming of theplastic material. As the upper base member 2 is softened, it is broughtinto position in relation to the lower base member 1, securing thevarious contact springs 8, 9 and 10in their correct positions in amanner described hereinafter. The lower base member 1 is not softenedduring such heating, and so its surfaces do not undergo any changeduring assembly. The lower base member 1 may be formed of thermoplasticmaterial having a higher melting point than that of the upper basemember 2, or, alternatively, may be formed of thermosetting material, orthe like.

The lower surface of the portion 2a of the upper base member 2 isprovided with a recess 14 located directly above the contact-making partof the contact spring 8, and a corresponding recess 13 is provided inthe upper surface of the portion la at a position underlying thecontact-making part of the lower contact spring 9. The recesses 13 and14 permit the outer ends of the stationary contact springs 8 and 9 toremain out of direct contact with the insulating base members 1 and 2,and the contacts are thereby made less vulnerable to mechanicalvibrations transmitted through the base members 1 and 2.

Referring to FIG. 3, an exploded view of a contact spring 19 isillustrated, in association with cooperating portions of the lower basemember 1 and the upper base member 2. The contact spring 19 correspondsto the contact spring 9 shown in FIGS. 1 and 2, but is formed in aslightly different shape than that shown in FIG. 2. The spring 19 has,at one end, a contact-making part 19b, and at the other end is connectedto a vertically extending terminal part 19a. The horizontal part of thespring 19 is joined to the terminal part 19a by a vertically disposedpart 19d, having a plurality of upwardly extending tabs 190. Duringassembly, the terminal part is lowered through a window 16 provided inthe lower base member 1, until the horizontal part of the spring 19 hasbeen lowered into contact with a horizontal supporting surface 17provided on the lower base member 1. The position of the surface 17 iscontrolled with great precision during manufacture of the member 1, sothat any manufacturing variations in the size and shape of the spring 19do not affect the positioning of the horizontal part of the spring 19.

During assembly, the upper base member 2 is lowered into associationwith the lower base member 1, and a wedge-shaped nose member 21 glidesdownwardly along the terminal part 190, bearing against a side edge ofthe window 16, and pressing the terminal part 19a and the verticallyextending part 19d firmly against the inside surface of a wall 22 formedon the base member 1. The position of this surface of the wall 22 iscontrolled with precision during manufacture, so that the contact spring19 is correctly positioned when the vertically extending part 19d liesagainst it.

Final assembly of the upper and lower base members 1 and 2 takesplace-by means of ultrasonic stapling, in which the upper base member 2is pressed downwardly against the lower base member 1 and is deformed byheat generated by the application of ultrasonic sound thereto until thecorrect assembled condition has been reached. In this process, the nose21 is simultaneously pressed downwardly into the window 16 and deformedin such a way as to tightly close the window 16, enveloping the upperportion of the terminal part 19a, and forming an impermeable barrierbetween the contact spring 19 and the terminal part 19a, where thesoldering takes place. Simultaneously, during assembly, the two upwardlydirected tabs 190 are pressed into the thermoplastic upper base member 2and are thus held rigidly in association therewith after the upper basemember 2 hardens on cooling. The amount of protrusion of the tabs 19cinto the upper base member 2 is not FIGS. 4 and 5 show, in two verticalsections which i are perpendicular to each other, the cooperation of thecontact spring 19 with the associated components of the assembly. Thesurface 17 support, the horizontal part of the contact spring 19, andthe cooperation of the upwardly extending tabs 190 with the upper basemember 2 is illustrated. The deformation of the nose 2], in a mannersuch as to fill the window 16, is also illustrated in FIG. 4. The loweredge of the part 19d is supported by the surface 24 of the lower basemember 1, as best illustrated in FIG. 5.

FIG. 6 illustrates, in exploded perspective view, the manner in whichthe contact spring 8 is assembled in relation to the lower base member 1and the upper base member 2. The contact spring 8 incorporates acontact-making part 8b at one end thereof and a downwardly dependingterminal part 8a at the other end thereof. The terminal part 8a isadapted to be inserted downwardly through a window 25 provided in thelower base member I, so that the horizontal portion of the contactspring 8 is supported on a horizontal surface 30, formed as the uppersurface of a wall 27. A deformable nose 26, depending from the upperbase member 2, is aligned with the window 25 and urges the contactspring 8 into firm association with the outer surface of the wall 27during assembly. A peg 28, provided on the upper base member 2, isreceived in an aperture 29, and the lower end of the peg is deformed toform a rivet head when assembly is complete.

The position of the surface 30 is controlled with great precision duringmanufacture of the base member 1. A plurality of depending noses 31 areprovided extending downwardly from the upper base member 2 and areadapted to urge the contact spring 8 against the surface 30. The noses31 may be formed without any particular tolerance since they aresoftened and deformed as much as necessary during assembly. Afterhardening on cooling, they function to maintain the contact spring 8 inposition against the surface 30.

FIG. 7 illustrates, in exploded perspective view, the manner in whichthe contact spring is assembled in association with the lower and upperbase members 1 and 2. The contact spring 10 is formed with a free end asillustrated in FIGS. 1 and 2, for cooperation with the dependingprojection 7 of the actuating member 5, and has a depending terminalpart 10a secured to the other end. The terminal part 10a is adapted topass downwardly through a window 32 provided in the lower base portion1, until the middle portion of the spring contact 10 is brought intocontact with an inclined surface 35, provided on the base member 1. Ashoulder 33 is provided adjacent the surface 35 on one side thereof, andan upwardly extending projection 34 is provided on the surface 35 on theopposite side of the contact spring 10 from the shoulder 33. Theshoulder 33 and the projection 34 together serve to maintain the contactspring 10 in the proper position prior to assembly of the base members 1and 2.

'35 during, and after, assembly.

During assembly, a peg 37, provided on the upper base portion 2, islowered into an aperture 39 provided in the lower base portion 1, andthe end thereof is softened to form a rivet head. The peg 37 has aconical portion 38 at its base, adjacent the surface 36, and the portion38 is adapted to be softened during assembly and to be squeezed betweenthe surfaces 35 and 36, outwardly from the peg 37, and against anarcuate notch provided in an edge of the contact spring 10, forcing thecontact spring 10 into aligned relationship against the shoulder 33. Inthis manner, correct alignment of the contact spring 10 is assuredduring assembly. The position of the shoulder 33, as well as theposition of the surface 35, are accurately controlled during manufactureof the lower base portion 1. During assembly, the ribs 40 are softenedand deformed as required, but upon hardening, function to maintain thespring 10 in position against the surface 35.

FIGS. 8 and 9 show two vertical cross sectional views showing theassociation of the contact spring 10 with the other elements of theassembly. FIG. 9 illustrates how the conical portion 38 of the peg 37has been urged against the spring 10 to force it into juxtaposition withthe'shoulder 33. FIG. 8 illustrates the manner in which the rivet head37a is formed at the lower end of the peg 37. A counterbore is providedin the lower portion of the aperture 39, to provide a shouldermaintaining the expanded rivet head 37a in position after assembly.

It will be appreciated from the foregoing that an easy tolerance isprovided in many of the dimensions of the electrical contact springs, aswell as in the manufacture of the upper base portion 2. All of thecritical surfaces are provided on the lower base portion 1, so that thispart alone must be'made with precision. In addition, the manner in whichportions of the upper base member are softened during assembly and urgedinto contact with the various contact springs so as to urge them intoalignment with the registration surfaces on the base member 1, permitsthe formation of a contact set with contact springs which are highlyaccurate in their positioning, even though no special measures are takento insure their alignment during assembly, other than simply insertingthe terminal parts into the appropriate windows of the base member 1,and then pressing the base member 2 into association with the lower basemember 1. It can thus be seen that the present invention lends itself toa high degree of mechanization, and may be readily and inexpensivelyassembled in large quantities.

In addition to the features described hereinabove, the assembled baseformed of the members 1 and 2 may also be provided with furtherrecesses, projections and the like, for the provision of othercomponents such as a grounding spring or a relay protection cap. Thenose 41 illustrated in FIG. 8 is, for example, provided for the purposeof securing a protective cap (not shown) in position.

Although the present invention has been specifically described in termsof a card-type relay, those skilled in the art will appreciate that itis not so limited, but may equally well be used with other relayconstructions. In

addition the present invention may be employed in the manufacture ofother assemblies in order to provide an efficient and highly accurateassembly process, which is highly adaptable to being mechanized.

What is claimed is:

l. A contact spring set for an electromagnetic relay comprising aplurality of electrical contact elements, and a block formed ofinsulating material and comprising first and second insulating membersadapted to support said contact elements, said first insulating memberbeing formed of thermoplastic material and said second insulating memberbeing formed of an inherently stable plastic material, said block havinga recess formed therein, said electrical contact elements having theircontact-making parts supported within said recess, one of said contactelements having a portion interposed between said two insulatingmembers, said two insulating members bearing against said one contactelement to maintain it in fixed position relative to said second member.

2. Apparatus according to claim 1, including a plurality of movablecontact elements, said movable contact elements being mounted on saidblock so that the motion of such movable elements defines a pair ofspaced parallel planes.

3. Apparatus according to claim 1, wherein said contact elements eachhave a portion interposed between said two interlocked members.

4. Apparatus according to claim 1 wherein said inherently stable memberis provided with means for supporting said contact elements.

5. Apparatus according to claim 4 wherein said contact elements arepressed against said supporting means by first insulating projectionsformed integrally with said deformable member.

6. Apparatus according to claim 1 wherein said two members areinterlocked by means of a riveted peg formed'integrally with one of saidmembers and received in an aperture provided in the other of saidmembers.

7. Apparatus according to claim 1 including a terminal connected withsaid one contact element and adapted to be soldered to an electricalconductor, said terminal extending through an aperture in one of saidmembers.

8. Apparatus according to claim 7 wherein said aperture is closed by adeformable portion of said other member.

9. Apparatus according to claim 7 wherein all of said contact elementscomprise electrically conductive springs interposed between said twomembers and terminal elements for each of said springs extending at anangle to said springs through apertures in said one member.

10. Apparatus according to claim 1 wherein the contact-making parts ofsaid contact elements are spaced from said block.

11. Apparatus according to claim 1 including a movable contact springmounted between inclined supporting surfaces disposed on said twomembers.

12. Apparatus according to claim 1 including means for urging one ofsaid contact elements laterally against a supporting wall formedintegrally with one of said members by a projection formed integrallywith the other said member.

13. Apparatus according to claim 1 wherein said one contact element hasa plurality of projections, said projections being adapted to enter oneof said members during assembly of said one member with said othermember.

14. Apparatus according to claim 1 including means formed integrallywith one of said members for supporting all of said contact elementspreparatory to assembling said two members together.

15. A method for the production of a contact spring set, including thesteps-of providing first and second insulating members adapted to beinterlocked to form a complete contact set assembly, providing aplurality of accurately positioned surfaces on said first member,

placing a plurality of contact elements on said accurately positionedsurfaces, superposing said second member over said contact elements, andsecuring said first and second members in fixed relation by each otherby deforming said second member.

16. The method according to claim 15 including the step of deforming aprojection integral with said second insulating member without deformingsaid second member as said projection is urged against a contact member.

17. The method according to claim 16 wherein said deforming takes placeduring heating resulting from the application of ultrasonic energy tosaid second member.

1. A contact spring set for an electromagnetic relay comprising aplurality of electrical contact elements, and a block formed ofinsulating material and comprising first and second insulating membersadapted to support said contact elements, said first insulating memberbeing formed of thermoplastic material and said second insulating memberbeing formed of an inherently stable plastic material, said block havinga recess formed therein, said electrical contact elements having theircontact-making parts supported within said recess, one of said contactelements having a portion interposed between said two insulatingmembers, said two insulating members bearing against said one contactelement to maintain it in fixed position relative to said second member.2. Apparatus according to claim 1, including a plurality of movablecontact elements, said movable contact elements being mounted on saidblock so that the motion of such movable elements defines a pair ofspaced parallel planes.
 3. Apparatus according to claim 1, wherein saidcontact elements each have a portion interposed between said twointerlocked members.
 4. Apparatus according to claim 1 wherein saidinherently stable member is provided with means for supporting saidcontact elements.
 5. Apparatus according to claim 4 wherein said contactelements are pressed against said supporting means by first insulatingprojections formed integrally with said deformable member.
 6. Apparatusaccording to claim 1 wherein said two members are interlocked by meansof a riveted peg formed integrally with one of said members and receivedin an aperture provided in the other of said members.
 7. Apparatusaccording to claim 1 including a terminal connected with said onecontact element and adapted to be soldered to an electrical conductor,said terminal extending through an aperture in one of said members. 8.Apparatus according to claim 7 wherein said aperture is closed by adeformable portion of said other member.
 9. Apparatus according to claim7 wherein all of said contact elements comprise electrically conductivesprings interposed between said two members and terminal elements foreach of said springs extending at an angle to said springs throughapertures in said one member.
 10. Apparatus according to claim 1 whereinthe contact-making parts of said contact elements are spaced from saidblock.
 11. Apparatus according to claim 1 including a movable contactspring mouNted between inclined supporting surfaces disposed on said twomembers.
 12. Apparatus according to claim 1 including means for urgingone of said contact elements laterally against a supporting wall formedintegrally with one of said members by a projection formed integrallywith the other said member.
 13. Apparatus according to claim 1 whereinsaid one contact element has a plurality of projections, saidprojections being adapted to enter one of said members during assemblyof said one member with said other member.
 14. Apparatus according toclaim 1 including means formed integrally with one of said members forsupporting all of said contact elements preparatory to assembling saidtwo members together.
 15. A method for the production of a contactspring set, including the steps of providing first and second insulatingmembers adapted to be interlocked to form a complete contact setassembly, providing a plurality of accurately positioned surfaces onsaid first member, placing a plurality of contact elements on saidaccurately positioned surfaces, superposing said second member over saidcontact elements, and securing said first and second members in fixedrelation by each other by deforming said second member.
 16. The methodaccording to claim 15 including the step of deforming a projectionintegral with said second insulating member without deforming saidsecond member as said projection is urged against a contact member. 17.The method according to claim 16 wherein said deforming takes placeduring heating resulting from the application of ultrasonic energy tosaid second member.